The invention relates to a rotary slide valve closure for metal melt containers having a bottom discharge opening, comprising a fixed refractory top block formed with a flow duct, and a rotary refractory discharge block formed with a flow duct and and which is in a sealing-tight relationship against the top block. The axis of rotation of the discharge block forms an acute angle with the vertical central axis of the flow duct, and the place of intersection of the axis of rotation with the central axis of the flow duct being is located in the cross-sectional plane of the discharge opening of the flow duct in the discharge block.
In the customary rotary slide valve closure with a vertical axis of rotation, when the slide valve plate is adjusted in the direction of heavier or lower throttling, the discharge opening and, therefore, the position of the emerging stream are displaced laterally together with the slide valve plate. In contrast, when the slide valve plate rotates around its axis in the closure as in the invention, the opening of the flow channel situated on the inside is guided in an arc of a circle and completely or partially opens or closes the flow channel, while the discharge opening maintains its position, so that the emerging stream of melt does not shift. This is advantageous in all casting operations in which the pouring stream must not shift, for example, when casting into a continuous chill mould or when introducing the stream of metal into the mould pouring gate during production of shaped castings.
A rotary slide valve of this kind is known from German AS 20 43 588, but it has disadvantages. For example, the perforated plate and slide valve plate, constructed in the form of frustoconical members, are disposed in a slide valve casing comprising an upper and lower part interconnected via a screwed connection. However, screwed connections are disadvantageous for heavy-duty steelworks operations. The axial position of the slide valve casing is adjusted in relation to the opening in the container bottom by intermediate rings. However, such an adjustment is unpractical for steelworks operations and can lead to inaccuracies of assembly. Moreover, the perforated plate and the slide valve plate are rigidly disposed on the slide valve casing, so that it is probably difficult to achieve an even bearing of the sealing and sliding surface of the perforated plate or the slide valve plate, more particularly since refractory members may have dimensional tolerances due to manufacture.
Other disadvantages are the construction of the rotary slide valve from many complicated parts, its large overall height, the difficulty of assembling and demounting the whole slide valve closure at the discharge opening of the vessel, and the complicated interchange of used refractory members. These disadvantages have probably contributed towards such rotary slide valve closures not being widely adopted, although steelworks and foundries require a slide valve closure in which the emerging stream of melt does not shift.